There has been known a technology of a so-called system ceiling for suspending a suspended ceiling including beams and ceiling panels through suspension bolts from a ceiling slab. For example, Patent document 1 discloses, as a technology relating to the system ceiling, a suspension metal connecting a suspension bolt to a suspended ceiling, the suspension metal being fixed to a ceiling slab. The suspension metal described in Patent document 1 supports a beam by sandwiching and holding the beam from the outside.
Further, Patent document 2 discloses, as a technology relating to the system ceiling, a ceiling structure including: suspension members suspended from a ceiling slab; rails fixed to the suspending members; and a panel frame hooked to the rails so that the ceiling panel is hooked and traversed between the rails. The suspension members described in Patent document 2 support the rails by inserting a base end side of each of the suspension members into an inside of each of the rails having a C-channel shape opened upward, to thereby engage the rail with the suspension member in the inside of the each of the rails.    [Patent document 1] Japanese Patent Application Laid-open No. 2007-146584    [Patent document 2] Japanese Patent Application Laid-open No. Hei 11-71849    [Patent document 3] Japanese Patent Application Laid-open No. Hei 07-62784    [Patent document 4] Japanese Patent Application Laid-open No. Hei 08-284302    [Patent document 5] Japanese Patent Application Laid-open No. 2000-355999    [Patent document 6] Japanese Patent No. 3004982    [Patent document 7] Japanese Utility Model Application Laid-open No. Hei 06-10429    [Patent document 8] Japanese Utility Model Application Laid-open No. Hei 06-20652    [Patent document 9] Japanese Patent Application Laid-open No. Hei 08-74374